| Summary: | 碩士 === 國立交通大學 === 工學院半導體材料與製程設備學程 === 106 === Taiwan’s semiconductor foundry industry holds up to 50% market share around the globe, which indicates that Taiwan plays a significant role in this foundry industry. Semiconductor products require many kinds of artificial chemicals during the manufacture. In recent years, due to the use of various chemicals, damage caused to human health and the environment has become a serious problem. People have become much aware and believed that environmental issues should be taken into consideration in the future development of semiconductor technology.
Perfluorooctanesulfonic acid (PFOS) and Pentadecafluorooctanoic acid (PFOA) are artificial synthetic perfluorinated compounds (PFCs) containing eight carbon atoms. Since hydrophobicity and oleophobicity are characteristics of carbon–fluorine bonds, such carbon–fluorine compounds are widely applied to waterproofing and anti-fouling, including textiles, oil paints, anti-corrosion topcoat for metals, and photoresists for photolithography of semiconductors. In semiconductor manufacture, PFOA added in photoresist coatings serves as a surfactant in order to lower the surface tension and to increase the homogeneity and smoothness of photoresist coatings.
However, PFOS and PFOA have an extremely high bioaccumulation potential and multiple toxicities. It has been proved in animal experiments that PFOA not only causes harm to respiratory and cardiovascular systems of human bodies but also is a carcinogen. People have been highly concerned about the global contamination caused by PFOA and PFOS. Around 2001, the United States took initiative to stop the production and use of PFOS. After 2004, the European Union also published the regulation to restrict and ban the use of PFOA, planning to achieve the goal of zero emissions of PFOA worldwide.
Substances such as PFOS and PFOA, which contain more than eight carbon chains in the fluorinated alkyl, are almost non-biodegradable in natural environments. In order to be eco-friendly, the surfactant for semiconductor photoresists should be changed into the one which is biodegradable and contains less than eight carbon chains in the fluorinated alkyl. However, if the carbon chains of the fluorinated alkyl-carbon compounds are reduced to less than six, the compounds’ capability of reducing surface tension is largely decreased. Moreover, the less the number of carbon atoms are, the more difficult the surfactant can achieve the effect in terms of lowering the surface tension. Suppliers of photoresists have been undertaking the development of substitutes for PFOA in recent years, and they also have been testing those substitutes to see whether they could achieve the desired effect as PFOA does.
Based on the appeal of environmental protection, this paper researches the processing efficiency (including the adhesive capacity, etching resistance, photolithographic reaction, and yield rate) of the new type of photoresist (BARC) with the new surfactant and the old type of photoresist (BARC). The paper aims to find out whether there is any difference in the processing efficiency between the two types of photoresists (BARC), and whether the new type of photoresist (BARC) could be eco-friendly as anticipated without reducing its efficiency in the process of semiconductor device manufacturing.
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